The present invention relates to a bag-in-box container for storing and carrying liquid or fine particles (with hereafter generally be named flowable products). More particularly the present invention relates to a bag-in-box container in which a casing is resistant to bulging due to a bulging inner bag.
A composite packaging container of a corrugated fiberboard box with a flexible plastic inner liner is known in the art. These disposable containers are used for storing and dispensing. For Example seasonings such as soy sauce, vinegar, food additives, beverages such as liquor and mineral water, or chemicals such as liquid developer, liquid fertilizer, adhesive and detergent. This composite packaging container is generally called a "bag-in-box".
The bag-in-box is issued to contain or shaped flowable products. These products exert internal pressure of the content directly to the side panel of the container. This internal pressure exerts a local concentration of stress which causes container to bulge or buckle The problem is exaggerated, when the box absorbs moisture while containers are piled up and stored. The result is that the containers overturn or the merchandise value is lowered.
Often, the containers are prevented from collapsing by decreasing the number of stages of piled-up containers. However, this is disliked by distributors. Alternatively, the container is made to withstand the internal pressure by decreasing its relative size.
For these reasons metallic containers having high rigidity such as cans remain preferable as liquid transportation containers.
However, though the metallic container are strong. They are also heavier and more difficult to recollect after use. Additionally, they require extra storage space when empty, cannot be folded, and have a higher transportation cost.
In contrast, the bag-in-box is lightweight because it uses a corrugated fiberboard box as its outer package and a thin-walled container made of flexible plastic or a bag as its inner package. Consequently, the transportation cost, the warehouse cost, and the distribution costs are diminished. Moreover, it is disposable and unnecessary to recollect the box after it becomes empty. After use, after the box is used, the outer package can be recycled as pulp resource and the relatively small plastic container serving as the inner package can easily be. Therefore, the bag-in-box has advantages that the labor and energy can be saved and the costs can be reduced. To date, a bag-in-box which, does not exhibit bulging has not been reported.
To prevent the bag-in-box from bulging, it is necessary to increase the strength of the side panel. Therefore, it is preferred to form the box by using double wall corrugated fiberboard or triple wall corrugated fiberboard and decease the height of the box. To reinforce the side panel of the box, there is an existing method of arranging a piece of corrugated fiberboard called a sleeve folded like a cylinder inside of the box.
However, by only inserting the sleeve made of a material different from that of the casing into the box, it is impossible to prevent the casing from bulging due to a bulged bag storing liquid. Moreover, this method is inferior in profitability and packaging characteristic including materials because the casing comprises a plurality of pieces. Therefore, this method is significantly limiting.
As another means for reinforcing the side panel of the box, it is attempted to use a Bliss type box. However, even the Bliss type box has problems that the box structure becomes complex, the productivity lowers, and the cost rises.
Moreover, a relatively small carton is known in which a reinforcement member approximately Z-folded is set to the center between faced side panels in order to prevent bulging. Though this carton is effective to store fine particles or a small solid material, it cannot be applied to a large bag-in-box for storing bags containing liquid.
As for a box, it is generally known that the bending strength of the side panel of the box or the compressive strength of the whole box is improved when a number of angles are formed by bending the material (corrugated fiberboard or paperboard sheet blank) of the side panel of the box. By using the above theory, a container is proposed which is constituted by extending a flap to the both ends of faced side panels of the box respectively and folding the flap toward the inside of a corner of the box and bonding it to the corner in order to reinforce the four corners of the box. (Refer to U.S. Pat. No. 4,056,223.)
The container disclosed in the above U.S. patent (be sure to refer to the enclosed U.S. Pat. No. 4,056,223) is a container for storing packaged cut meat, having a structure in which four connected corner reinforcement members 121a through 121d and 122a to 122d are bonded to the both sides of side panels 116 and 117 so as to form a triangular space between the adjacent side panels 113 and 114 and thereby form a triangular cylindrical reinforcement column P inside of each corner of the box as shown in FIG. 15. Prior art This patent publication contemplates reinforcing the four corners of the box to improve the overall strength i.e., buckling strength, of the underlying box, such as when during transportation. For purposes of reinforcing the four corners of the box, flaps 121a through 121d, 122a through 122d are extended to both ends of the faced side of the panels of the box and folded to bond to the inside of the box corner.
However, the box embraced by this prior art invention fails to teach or suggest the bag-in-box concept of the present invention. Also, this publication is devoid of any teaching suggesting the side panel of the container itself or the novel way in which the presently contemplated box-in-bag is able to minimize bulging due to internal pressure imparted by the content of the container.
Indeed, it is a feature of the present invention that casing of the bag-in-box is such that an oblique surface of the octagonal inner cylinder exerts a pulling effect on the side panel of the quadrangular casing inward, thus preventing bulging of the box. The present invention aims to minimize bulging wherein the construction of the bag satisfies the formula Lp&lt;alpha p or beta p in cases where the stress is internal pressure of the oblique surface of the octangular inner cylinder as Lp and the stress of the internal to internal pressure of the fixed surface between the inner cylinders and the side panel of the casing as alpha p or beta p. In the present invention, it is advantageous that the bag-in-box is provided to prevent protruding corners from being formed in the box so as to form the inner bag prevented from being broken due to contact with the corner. In this case, however, a stepped portion with a thickness equivalent to the thickness of one or two material sheets is produced in the inner surface of the container. The stepped-portion appears as a right- or an acute-angle corner when observing the cross section of the container. Therefore, when the above container is used as, for example, the outer package of the bag-in-box for storing liquid and an inner bag B made of flexible plastic is set in the container, the surface of the plastic inner bag B tends to be scratched due to the angles of the container inside as shown in FIG. 16 which shows a prior art bag. Moreover, in the case of a liquid transportation container, liquid easily causes rocking splash due to vibrations and shocks during transportation. When rocking occurs, the plastic inner bag B moves as shown by a chain line in FIG. 16. A film forming the bag receives a repetitive bending force due to rocking, the bag is deformed and contacts the wall surface of the container, and resultantly, the bag is easily broken. When the bag is rubbed on a corner or receives a repetitive modified bending force, a pin hole may easily be produced on the bag due to at least one of the factors. When the pin hole is produced, the liquid tends to leak.